Beyond a cage, what other chassis mods (excluding shock/springs) are there? I would be curious about low hanging fruit for higher powered cars. Upper stress bars, larger sway bars, seam welding the pinch joints... is there more for this chassis?

Ok, here is an actual weight of an LS1 with accessories, intake manifold, exhaust headers, crossmember, and light weight clutch (total flywheel clutch combo is 32 lbs). That puts my LS at 405 as it sits in the car. I can't believe that I don't have a weight pic of a 968 engine considering how many I killed over the years SmileWavy

http://forums.pelicanparts.com/uploa...1397829696.jpg

the porsche weight numbers are with flywheel, clutch, AC and alternator. your 437# is what i expected to see. adding in the AC and alternator (which i don't see in that pic) would make your engine about 460lbs. that is 100# more than a 944 engine and 80# more than a 968 engine. that is before adding the larger cooling and bracing and such.

bang on what i have always said. thanks

Alternator is on the engine, located on the drivers side down low. No AC or power steering pump. But it also has exhaust headers and crossmember bolted on, so subtract off that weight.

Although I did not weigh the supercharged 968 engine that this one replaced, I can tell you that there was virtually no difference in car weight between the SC-968 powered car and the LS-powered car.

yeah - a centrifugal SC kit complete adds about 40#. it would be down to around 40-50# difference, plus the weight of the added cooling capacity and bracing for the torque, which would tend to be about another 30-40#. not the end of the world, and pretty easy to rebalance by merely moving the battery to the rear. the big differences are when talking about going from a normally aspirated 944 to a V8, which is what most of the guys are doing.

of course then you need to add in the weight of the larger brakes to stop the faster car (no matter what power plant), the heavier axles, larger sway bars, yada yada. it all adds up. but then, that's a large part of why cars today are so much heavier, in spite of the lighter materials. the chassis are stiffer, brakes are bigger, and everything else that makes the cars so much better built. no free lunch

i think one of the first things i'd do with a high-power engine would be making a subframe of sorts linking all the suspension points and large bolts on the body, mounted underneath, to add some stiffness without intruding like a cage.

paired with one of your interior roll bars, flash, it could make a big difference. you still make those?

agreed. the bottom of these cars is pretty flexy. makes for a very comfortable ride, but being a unibody design, there are limits to what it can absorb and transfer.

yes, i still make them, but they are done to order. i don't really stock anything anymore, and anything i do now is based on advanced orders. keeps the wife happy that way, as i'm not constantly messing with cars anymore.

Will stock tires even put down enough power to twist the chassis? Somehow I doubt it...

There's always traction control and proper tire size... exactly how new high HP, OEM manufactured cars do it.

traction control stems out of federally required stability control for new cars after 2010? iirc.


the king of V8 944s, a back-halfed 944 with 997GT3 suspension/brakes all around, recently discovered that the torque tube bows under high load.

as in, the 6 ft steel pipe in the middle of the car actually bends upwards in the middle due to countertorque from the axles, twisting the transaxle.

so yea, the chassis will flex and twist.

not something id worry about so much, since he's over 6.5L and pushing in the mid 600s HP, but if it happens to him, it happens on the other cars, just less.

yup - i can feel the shaft inside flexing at only a bit over 300 lb/ft, and i have super bearings and everything. much more than that and i think i'd break something soon enough. when i thought about pushing bigger numbers, i toyed around with the idea of reworking the whole assembly, going carbon fiber on the tube, a tubular shaft, and all that, but bailed when i thought about it and realized i couldn't actually use the power i already had, let alone go for more.

had i the time and budget, i'd look into thickening the walls of the tube and fitting a larger, hollow driveshaft (aluminum perhaps?)

the TT is just the right size (3.48" iirc) to fit a 3.5" ID schedule 40 steel pipe around snugly and weld together for extra stiffness. good luck bending that thing...probably break off the cast Al first.

I would think you could gusset the tube full length in a couple places to stiffen it up if that became the fuse.

Hmm, lets see. I am using a TT from the 924S that I bought years ago. I first used the car as a DE car, then added a 968 engine to that car and raced it for years. After totaling the car, I moved as much as I could to a roller 944S, including moving the TT. That car was raced with an SC-968 engine for 2 years before switching to an LS1 engine. I've been going strong with the LS for 3+ years, both racing and DE's, still using that same TT that has never been rebuilt. Guess my ass is not as sensitive, because if that TT is flexing, I sure don't feel it.

like i said, if it's happening to him, then it's going to be happening to the rest of us, just to lesser degrees due to variances in amount of torque output...he is running about the stickiest tires there are though which contributes alot to the counterforce.

chances are your LS1 isn't over 600HP/550ftlbs, i assume...but even at 350-400, on street tires, it *should* be happening, but not enough to worry about.

I can feel the windup from the 968 DMF under certain circumstances, I am not sure how one could feel the torque shaft flex with that in play.

i had a solid flywheel for quite a while. pretty easy to feel, and the reason i went to super bearings, which helped but did not eliminate it. i have since changed back to the DMF, and don't notice it as much, but it's still there.